A number of systems are known for pouring concrete in place to form floors, sidewalks, and the like. Some of the systems use forms to hold the concrete in place while it is poured, during setting, and then remain in place as part of the permanent installation. These systems, at least the ones that are known to the inventor, appear to suffer from a number of serious drawbacks which detract from their use efficency and hence popularity.
One particular system available in the United States is manufactured and sold by Leav-er-ite Manufacturing Company Inc., Sheridan, Wy., U.S.A. That system involves the use of forms of light gauge metal, such as steel, which is preformed so that it can be installed in place without modification at the job site. The system consists of steel concrete retaining sidewalls which have a plurality of spaced perforations or slots along the length of the sidewall. These sidewalls are laid end to end on either side of the proposed sidewalk and are held in place by steel cross-members. Clips with projections that fit through the slots in the sidewall are used to hold the cross-members in place relative to the side walls. The cross-members are not as deep as the sidewalls, and hence, when the concrete is poured, the cross-members are buried by concrete and obscured from view. The cross-members remain in place as part of the permanent concrete installation. The sidewalls and sidewall clips are held in place by sheet metal stakes which are driven into the ground at appropriate locations along the length of the sidewall. Sheet metal corner pieces are also available to enable the sidewalls to be used in forming inside and outside corners.
One serious difficultly with the Leav-er-ite system is that the slots in the sidewalls are very narrow in order to provide a snug relatively wiggle-free fit with the sidewall clips that are attached to the cross-members. It has been found in practice on the construction site that the slot and clip projection tolerances provided are too fine to enable rough and ready installation. Considerable trial and error tinkering must be done in order to fit the pieces together, particularly on uneven terrain. Simple errors of variations in position of one-sixteenth of an inch prevent the clips fitting through even the closest of the slots in the sidewalls. When this happens, the stakes holding the sidewalls to the ground must be pulled and driven in again at a slightly different location, with no assurance that the second position will be any better than the first position. The system is therefore inherently labour intensive, notwithstanding that the system is supposed to minimize labour input.